title: Drop-port study of microresonator frequency combs: power transfer, spectra and time-domain characterization.
abstract: We use a drop-port geometry to characterize frequency combs generated from silicon nitride on-chip microresonators in the normal group velocity regime. In sharp contrast with the traditional transmission geometry, we observe smooth output spectra with comparable powers in the pump and adjacent comb lines. The power transfer into the comb may be explained to a large extent by the coupling parameters characterizing the linear operation of the resonances studied. Furthermore, comparison of thru- and drop-port spectra shows that much of the ASE noise is filtered out by transmission to the drop-port. Autocorrelation measurements are performed on the drop-port output, without the need to filter out or suppress the strong pump line as is necessary in thru-port experiments. Passively mode-locked pulses with low background are observed in a normal dispersion microcavity.
authors.forename: Pei-Hsun
authors.initials: PH
authors.lastname: Wang
authors.forename: Yi
authors.initials: Y
authors.lastname: Xuan
authors.forename: Li
authors.initials: L
authors.lastname: Fan
authors.forename: Leo Tom
authors.initials: LT
authors.lastname: Varghese
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Xue
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Leaird
authors.forename: Minghao
authors.initials: M
authors.lastname: Qi
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Weiner